I am probably the last person to hear about this. Pandora is web radio for the Music Genome Project. Songs are given attributes, and you select music based on the attributes and artists you like. The music, from the Internet, plays on computers and I think it will also play on a mobile phone.
As I write this I'm listening to Billie Holiday sing Ain't Misbehavin'. I'm just as likely to hear Pink Martini or Diana Krall on this "station." I also have stations set up for classical pianos and big band jazz. Oh, this is good. Has iTunes music selection beat all to hell. Sure makes waiting for my government to bail out Wall Street more pleasant!
A co-worker at the library told me about Pandora and I promptly forgot until I saw a news article about a webcasting bill that passed. New law will allow Pandora to stay in business because they will be able to negotiate lower royalty payments.
Now playing: Jane Monheit, new to me, singing Hit the Road to Dreamland. Pandora picked it out based on other things I liked and it chose well. I like it.
And there's more. I haven't even started listening to the classical piano stuff yet.